Hyperosmolar Hyperglycemic State

Hyperosmolar hyperglycemic state (HHS) is a life-threatening hyperglycemic crisis driven primarily by profound dehydration and hyperosmolality, not acidosis. The person has enough circulating insulin to suppress most lipolysis and ketone production, but not enough insulin to control glucose. Plasma glucose rises dramatically. Once the kidneys cannot reabsorb the filtered glucose, glucose spills into urine and pulls water with it. This osmotic diuresis becomes a large, ongoing fluid loss. A person who is ill, frail, cognitively impaired, or unable to access fluids may not replace that loss. Extracellular volume falls, renal perfusion worsens, glucose clearance declines, and hyperglycemia escalates. The increasingly concentrated blood draws water out of cells, including brain cells, which explains why altered cognition is such a prominent feature. HHS most often occurs in adults with type 2 diabetes, but up to one in five people presenting with HHS have no previous diabetes diagnosis. Infection, reduced oral intake, missed diabetes therapy, and medications that raise glucose or promote fluid loss can turn previously compensated hyperglycemia into crisis. HHS and diabetic ketoacidosis (DKA) are not opposite ends of a neat...